Cut-out sintered ceramic sheet and method of manufacturing the same

ABSTRACT

A method of manufacturing a cut-out sintered ceramic sheet having a complex shape and a cut-out sintered ceramic sheet made according to the method, the method including forming a ceramic green sheet, sintering the formed ceramic green sheet, adhering a plastic resin film onto which adhesive is applied on at least one surface of the sintered ceramic sheet, and shearing the sintered ceramic sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application SerialNo. JP2011-248110 filed Nov. 11, 2011 and International PatentApplication Serial No. PCT/JP2012/004604 filed Jul. 19, 2012, which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a cut-out sintered ceramic sheet, andto a method of obtaining a cut-out sintered ceramic sheet manufacturedaccording to a method including a first step of forming a ceramic greensheet, and a second step of sintering the formed ceramic green sheet.

BACKGROUND ART

In recent years, sintered ceramic sheets have become widely used inelectronic appliances such as cell phones and personal computers due totheir superior properties. Such cut-out sintered ceramic sheets can beprocessed into various shapes to make further use of their superiorproperties.

One known shape-processing method for a sintered ceramic sheet includesprocessing the sheet into a desired shape at the ceramic green sheetstage. A sintered ceramic sheet obtained by this method produces aprocessed shape based on a shrinkage factor of the ceramic green sheetexpected during the course of sintering. Typically, as shown in FIG. 11,when a ceramic green sheet 11 is sintered, the sintered ceramic sheet 12shrinks be about 20%. One problem is that a difference can occur betweenthe designed size calculated included the shrinkage factor, and theactual size of the sintered ceramic sheet obtained.

One solution to this problem is thus to process the sintered ceramicsheet after sintering. For example, Japanese Patent ApplicationPublication No. 2002-359317 discloses procedures to obtain a cut-outsintered ceramic sheet of desired dimensions by performing a laserprocess and a dicing process on the sintered ceramic sheet.

A disadvantage of dicing is that dicing requires that the rotary knifedirectly contact the sintered ceramic sheet during cutting, making itimpossible to process the sintered ceramic sheet into complex shapes. Adisadvantage of laser processing is that heat is generated at the pointof the laser focus, which can change the properties of the cut-outsintered ceramic sheet. Further, since longer time is required toprocess a complex shape, production efficiency decreases, and processingcosts increase.

To overcome the disadvantages of the prior art processes, the presentinvention provides a procedure by which a sintered ceramic sheet can beprocessed quickly into a complex shape, and a cut-out sintered ceramicsheet can be obtained with very high dimensional accuracy.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method for producing acut-out sintered ceramic sheet with high dimensional accuracy includingthe steps of forming a ceramic green sheet, sintering the formed ceramicgreen sheet, and cutting the sintered ceramic green sheet using acutting module, such as a die.

In another aspect, the method uses a ceramic green sheet as a rawmaterial and is capable of rapidly manufacturing a cut-out sinteredceramic sheet having an outer shape and/or inner shape that are smallerthan a planar shape of a sintered ceramic sheet obtained by sinteringthe ceramic green sheet, and with high dimensional accuracy.

In another aspect, a method for manufacturing a cut-out sintered ceramicsheet includes a first step of obtaining a formed ceramic green sheet byforming the ceramic green sheet, a second step of obtaining a sinteredceramic sheet by sintering the formed ceramic green sheet, a third stepof obtaining a film-adhered ceramic sheet by adhering a plastic resinfilm onto which adhesive is applied on at least one surface of thesintered ceramic sheet, and a fourth step of shearing the film-adheredceramic sheet. By employing such a procedure, since the sintered ceramicsheet is sheared instead of the formed ceramic green sheet, nodimensional deformation is exhibited. Since a distance along which acutting module is moved is short, the sintered ceramic sheet can quicklybe cut.

In another aspect, the fourth step may include shearing the film-adheredceramic sheet between the edges of upper and lower dies.

In another aspect, the fourth step may include directly or indirectlypressing the film-adhered ceramic sheet by the first or second pressingmodule against the contacting surfaces of the upper and lower dies, andshearing the film-adhered ceramic sheet between the edges provided oncontacting surfaces of the upper and lower dies.

In another aspect, the fourth step may include a first substep ofsandwiching the film-adhered ceramic sheet between the upper die and thesecond pressing module, juxtaposing the lower die to the second pressingmodule, and providing clearance between the edges of the upper and lowerdies, and a second substep of shearing the film-adhered ceramic sheet bymoving the upper and lower dies up and down relative to one another.

In another aspect, the fourth step may include a first substep ofsandwiching the film-adhered ceramic sheet between the lower die and thefirst pressing module, juxtaposing the upper die to the first pressingmodule, and providing clearance between the edges of the upper and lowerdies, and a second substep of shearing the film-adhered ceramic sheet bymoving the upper and lower dies up and down relative to one another.

In another aspect, the fourth step may include a first substep ofsandwiching the film-adhered ceramic sheet between the upper die and thesecond pressing module, juxtaposing the first pressing module to theupper die, and the lower die to the second pressing module, andproviding clearance between edges of the upper and lower dies, and asecond substep of shearing the film-adhered ceramic sheet by moving theupper and lower dies up and down relative to one another.

The cut-out sintered ceramic sheet may include a side surface, theentire surface of which is a fracture surface having reliefs.

In another aspect, a plastic resin film may be adhered onto at least oneof the upper and lower surfaces of the cut-out sintered ceramic sheet.

In another aspect, thee plastic resin film covering one of the upper andlower surfaces may extend to an end portion of the cut-out sinteredceramic sheet, and may be adhered up to the end portion.

According to the present invention, it becomes possible to manufacture acut-out sintered ceramic sheet with a complex shape having superiordimensional accuracy at a very high production efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a step of manufacturing a cut-out sintered ceramic sheet;

FIG. 2 is a partial cross-sectional diagram of a shearing device when asintered ceramic sheet is set;

FIG. 3 is a partial cross-sectional diagram of the shearing devicebefore shearing the sintered ceramic sheet;

FIG. 4 is an enlarged cross-sectional diagram of a C portion of FIG. 3;

FIG. 5 is a partial cross-sectional diagram of the shearing device afterhaving sheared the sintered ceramic sheet;

FIG. 6 is an enlarged cross-sectional diagram of a D portion of FIG. 5;

FIG. 7 is a diagram taken along an arrow B-B of FIG. 2;

FIG. 8 shows another step of manufacturing the cut-out sintered ceramicsheet;

FIG. 9 is a cross-sectional diagram of a film-adhered ceramic sheet;

FIG. 10 is a partial cross-sectional diagram of the shearing device whenthe film-adhered ceramic sheet is set;

FIG. 11 is a diagram showing shrinkage states of a ceramic sheet beforeand after sintering;

FIG. 12 shows a cut-out sintered ceramic sheet according to a firstembodiment;

FIG. 13 is a diagram taken along an arrow E-E of FIG. 2 in the firstembodiment;

FIG. 14 shows a cut-out sintered ceramic sheet according to a secondembodiment;

FIG. 15 is a diagram taken along the arrow E-E of FIG. 2 in the secondembodiment;

FIG. 16 shows a cut-out sintered ceramic sheet according to a thirdembodiment;

FIG. 17 shows a cut-out sintered ceramic sheet according to a fourthembodiment;

FIG. 18 is a diagram taken along the arrow E-E of FIG. 2 in the fourthembodiment;

FIG. 19 shows a cut-out sintered ceramic sheet according to a fifthembodiment;

FIG. 20 is a diagram taken along the arrow E-E of FIG. 2 in the fifthembodiment;

FIG. 21 is an SEM image of a fracture surface of a film-adhered ceramicsheet; and

FIG. 22 is a partial perspective diagram of a sintered ceramic sheetbefore shearing.

DESCRIPTION OF THE EMBODIMENTS

In the description that follows, a cut-out sintered ceramic sheet refersto a piece of sintered ceramic sheet obtained by cutting a sinteredceramic sheet into smaller areas. Specifically, FIG. 12 shows a cut-outsintered ceramic sheet 13 with a small area obtained by shearing alarger sintered ceramic sheet 6.

As shown in FIG. 1, a manufacturing process of the cut-out sinteredceramic sheet includes the following steps:

(1) Ceramic green sheet forming step including forming a ceramic greensheet by a doctor blade method, an injection method and the like, andthereafter cutting it into an appropriate size;

(2) Sintering step including obtaining a sintered ceramic sheet bysintering the obtained ceramic green sheet in the first step in asintering furnace at an appropriate temperature; and

(3) Shearing step including obtaining a cut-out sintered ceramic sheetby shearing the obtained sintered ceramic sheet into a desired shape.

As shown in FIG. 22, as principles of a shearing method, firstly thesintered ceramic sheet 6 is mounted on a lower die 4 having an edge 7 b,and then an upper die 3 having an edge 7 a is lowered in a Z direction.

In order to shear the sintered ceramic sheet 6, a shearing device 1 asshown in FIG. 2 is used. The shearing device 1 includes an upper-sidedie 2 a and a lower-side die 2 b. As in FIG. 2, the upper-side die 2 aincludes the upper die 3 and a first pressing module 5 a. The lower-sidedie 2 b includes the lower die 4 and a second pressing module 5 b. Abottom surface of the upper die 3 and an upper surface of the secondpressing module 5 b have a desired shape to be obtained when thesintered ceramic sheet 6 is sheared. The lower die 4 and the firstpressing module 5 a are juxtaposed to the second pressing module 5 b andthe upper die 3, respectively. That is, the upper die 3 and the lowerdie 4 are diagonally arranged. Further, the upper die 3 and the lowerdie 4 have the edges 7 a, 7 b, respectively that are substantially at aright angle. The angle of the edges improves as the angle moves toward aright angle.

As shown in FIG. 3, the sintered ceramic sheet 6 is set between theupper-side die 2 a and the lower-side die 2 b, and the sintered ceramicsheet 6 is directly pressed by a contacting surface 8 of the upper die 3and a contacting surface 8 of the second pressing module 5 b, and fixedthereby. The contacting surface refers to a surface by which the upperdie 3, the lower die 4, the first pressing module 5 a, or the secondpressing module 5 b makes contact with the sintered ceramic sheet 6.Accordingly, by pressing the sintered ceramic sheet 6 by the secondpressing module 5 b and fixing the same thereby, since warpage in thesintered ceramic sheet 6 upon shearing the sintered ceramic sheet 6 isprevented, dimensional accuracy can be improved.

Next, the lower die 4 is juxtaposed to the second pressing module 5 b.At this occasion, as shown in FIG. 4, a predetermined clearance X isprovided between the upper die 3 and the lower die 4. The clearance Xrefers to a gap formed between the upper die 3 and the lower die 4 uponperforming the shearing.

Then, as shown in FIGS. 5 and 6, when the upper die 3 and the lower die4 are relatively moved up and down, the sintered ceramic sheet 6 issheared between the upper die edge 7 a and the lower die edge 7 b, andcan be formed into the desired shape. Relatively moving up and down maymean to lower the upper die 3, to raise the lower die 4, or to move theupper die 3 and the lower die 4 simultaneously. In this case, as shownin FIG. 6, a distance A by which the dies are moved must at least be adistance equal to or more than a thickness of the sintered ceramic sheet6. Further, a portion 6 b that is not included in the desired shape ofthe sintered ceramic sheet 6 may be sandwiched by the lower die 4 andthe first pressing module 5 a and fixed thereby, and after havingjuxtaposed the upper die 3 to the first pressing module 5 a, the upperdie 3 and the second pressing module 5 b may be displaced up and down sothat the sintered ceramic sheet 6 is sheared between the edges of theupper die 3 and the lower die 4 to be formed into the desired shape.Further, when the shearing is performed by having fixed the cut-outsintered ceramic sheet 6 a by the upper die 3 and the second pressingmodule 5 b, and in addition having fixed the portion 6 b that is notincluded in the desired shape by the lower die 4 and the first pressingmodule 5 a, due to substantially an entire surface of the sinteredceramic sheet being fixed, the cutting can be performed with the bestdimensional accuracy. Further, as in FIG. 7, when the cutting isperformed along a B-B section in FIG. 2 and seen in a direction of anarrow, since the sintered ceramic sheet 6 is sheared between the edgesof the upper die 3 and the lower die 4 so as to be torn in an up anddown (Y1, Y2) direction, the cut-out sintered ceramic sheet 6 a comes tohave the desired shape at the same time as being subjected to theshearing.

When such a shearing device 1 is used, the sintered ceramic sheet 6 canquickly be processed into a complex shape, and in addition the cut-outsintered ceramic sheet 6 a can be obtained with a very high dimensionalaccuracy. Further, the upper and lower side dies 2 a and 2 b of theshearing device 1 employ a mechanism wherein each upper die 3 and lowerdie 4 are moved up and down by a predetermined load, e.g. conventionallifting mechanisms such as hydraulic lifting or mechanical lifting.Further, the contacting surfaces of the pressing modules 5 a and 5 bpositioned in the upper and lower side dies 2 a and 2 b may be made withthe same material as the contacting surface of the upper and lower dies3 and 4 (e.g. steel). Moreover, a processing condition of the shearingdevice such as a load, may be designed by those skilled in the artdepending on a thickness, material, or size of the ceramic sheet.

Although the sintered ceramic sheet 6 can be sheared in the abovemethod, it is vulnerable to breakage if the sintered ceramic sheet hasprojections thereon, since pressure accumulates at the protrusions. Dueto this, as shown in FIG. 8, a plastic resin film adhering step isadded. When plastic resin films 9 are adhered to the sintered ceramicsheet 6, a cross section thereof turns out to be as shown in FIG. 9, anda film-adhered ceramic sheet 10 is obtained. Although the film-adheredceramic sheet 10 of FIG. 9 has the plastic resin films 9 on bothsurfaces of the sintered ceramic sheet 6, the plastic resin film 9 maybe adhered only to one surface. When the plastic resin film 9 is adheredas described, the pressure directly exerted onto the sintered ceramicsheet 6 during the shearing is dispersed, and as a result, the sinteredceramic sheet 6 becomes resistive to breakage at portions other than thedesired shearing portion. Accordingly, as in FIG. 10, when thefilm-adhered ceramic sheet 10 is set on the shearing device 1 and thefilm-adhered ceramic sheet 10 is subjected to the shearing similar tothe above method, a cut-out sintered ceramic sheet 6 a with furtherimproved dimensional accuracy can be obtained.

It is preferred that the clearance X in shearing the film-adheredceramic sheet is substantially 5-50 μm. In other words, a clearance X ofsubstantially 5-50 μm reduces the occurrence of large burrs on thefracture surface or deformation of the end edge of the fracture surfaceof the ceramic sheet, and therefore allows a shearing process with finerand higher dimensional accuracy. Further, when the sintered ceramicsheet 6 (namely, the film-adhered ceramic sheet 10) to which the plasticresin film 9 adheres is sheared with the clearance X, both the sinteredceramic sheet 6 and the plastic resin film 9 are fractured along thefracture surface. As a result, the plastic resin film 9 adheres up tothe edge of the cut-out sintered ceramic sheet 6 a. However, thoseskilled in the art may optionally design the clearance X, so thetechnical scope of the present invention is not limited.

The material for the sintered ceramic sheet of the present embodimentsmay be selected from the following group: alumina, zirconia, magnesia,titania, silica, aluminum nitride, silicon nitride, silicon carbide,ferrite, cordierite and mullite. The plastic film of the presentembodiments may include polyester, polyimide, polyimide varnish, epoxyresin and metallic foil such as copper, aluminum and SUS. Further, theadhesive for adhering the plastic film onto the sintered ceramic sheetmay be selected from acrylic adhesive, silicon adhesive and epoxypressure sensitive adhesive, and such. However, the technical scope ofthe present invention is not limited to the above materials and thoseskilled in the art may select the materials appropriately.

EXAMPLE 1

As a first embodiment, FIG. 12 is an embodiment of the cut-out sinteredceramic sheet obtained by using the present invention. As shown in FIG.13, when the upper-side die 2 a is seen from just below, the upper die 3and the pressing module 5 a are adjacent to one another. On the otherside, when the lower-side die 2 b is seen from just above, the upper die3 of FIG. 13 has the same shape to correspond to the second pressingmodule 5 b, and the first pressing module 5 a has the same shape tocorrespond to the lower die 4. When such an upper-side die 2 a and alower-side die 2 b are prepared, and the sintered ceramic sheet 6 issheared in the manufacturing process shown in FIGS. 1 and 8, the cut-outsintered ceramic sheets 13 that are sheared into two pieces can beobtained.

EXAMPLE 2

As a second embodiment, FIG. 14 is another embodiment of a cut-outsintered ceramic sheet obtained by using the present invention. As shownin FIG. 15, when an upper-side die 2 a is seen from just below, upperdies 3 and first pressing modules 5 a are positioned adjacent to oneanother, and the upper dies 3 are arranged diagonal to one another andthe first pressing modules 5 a are arranged diagonal to one another. Onthe other hand, as of a lower-side die 2 b, when seen from just above,the upper dies 3 of FIG. 15 have the same shape to correspond to secondpressing modules 5 b, and the first pressing modules 5 a have the sameshape to correspond to lower dies 4. When such an upper-side die 2 a anda lower-side die 2 b are prepared, and the sintered ceramic sheet 6 issheared in the manufacturing process shown in FIGS. 1 and 8, cut-outsintered ceramic sheets 14 that are sheared into four pieces can beobtained.

EXAMPLE 3

As a third embodiment, FIG. 16 is another embodiment of a cut-outsintered ceramic sheet obtained by using the present invention. When anupper-side die 2 a is seen from just below, similar to the secondembodiment, upper dies 3 and first pressing modules 5 a are positionedadjacent to one another, the upper dies 3 are arranged diagonal to oneanother, the first pressing modules 5 a are arranged diagonal to oneanother, and further, this shape is connected in a grid manner. Similarto the first embodiment, a lower-side die 2 b has the same shape inwhich the upper dies 3 correspond to second pressing modules 5 b, andthe first pressing modules 5 a correspond to lower dies 4. When such anupper-side die 2 a and a lower-side die 2 b are prepared, and thesintered ceramic sheet 6 is sheared in the manufacturing step shown inFIGS. 1 and 8, cut-out sintered ceramic sheets 15 that are sheared intoa plurality of pieces are obtained.

EXAMPLE 4

As a fourth embodiment, FIG. 17 is another embodiment of a cut-outsintered ceramic sheet obtained by using the present invention. As shownin FIG. 18, when an upper-side die 2 a is seen from just below, an upperdie 3 has a star-shaped portion, and a first pressing module 5 a has aportion other than the star-shaped portion. On the other hand, when alower-side die 2 b is seen from just above, a second pressing module 5 bis the star-shaped portion, and a lower die 4 is the portion other thanthe star-shaped portion. When such an upper-side die 2 a and alower-side die 2 b are prepared and the sintered ceramic sheet 6 issheared in the manufacturing process as shown in FIGS. 1 and 8, astar-shaped cut-out sintered ceramic sheet 16 is obtained. In otherwords, each edge of the contacting surface of the upper die 3 (or thesecond pressing module 5 b) and the lower die 4 (or the first pressingmodule 5 a) has the same shape as the desired shape on the cut-outsintered ceramic sheet (namely, a star shape). Accordingly, in theshearing process above, the star-shaped cut-out sintered ceramic sheet16 is sheared off from the sintered ceramic sheet 6 (or the film-adheredceramic sheet 10) along the edge. Then, one film-adhered ceramic sheet10 (or the sintered ceramic sheet 6) is separated into thedesired-shaped (namely, star-shaped) cut-out sintered ceramic sheet 16and the rest of the outer portion. In this way, a desired-shaped cut-outsintered ceramic sheet can be obtained by optionally setting the shapeof the upper and lower dies. Furthermore, since a margin which is theouter portion of the cut-out sintered ceramic sheet is sheared off in asingle shearing process, the cut-out sintered ceramic sheet can berapidly and accurately produced. In addition, providing the upper-sidedie 2 a and the lower-side die 2 b with a plurality of separated upperand lower dies 3, 4 allows that a plurality of desired-shaped cut-outsintered ceramic sheets to be sheared off from a single film-adheredceramic sheet 10 in a single shearing process.

EXAMPLE 5

As a fifth embodiment, FIG. 19 is another embodiment of a cut-outsintered ceramic sheet obtained by using the present invention. As shownin FIG. 20, when an upper-side die 2 a is seen from just below, an upperdie 3 has a doughnut-shaped portion, and a first pressing module 5 a hasportions other than the doughnut-shaped portion. On the other hand, whena lower-side die 2 b is seen from just above, a second pressing module 5b is the doughnut-shaped portion, and a lower die 4 is the portionsother than the doughnut-shaped portion. When such an upper-side die 2 aand a lower-side die 2 b are prepared and the sintered ceramic sheet 6is sheared in the manufacturing process as shown in FIGS. 1 and 8, adoughnut-shaped cut-out sintered ceramic sheet 17 a is obtained. Inother words, the upper die 3 has an annular contacting surface withinner and outer edges. Two cut-out sintered ceramic sheets are shearedoff from the film-adhered ceramic sheet 10 along the inner and outeredges. That is, one film-adhered ceramic sheet 10 (or the sinteredceramic sheet 6) is separated into the first annular cut-out sinteredceramic sheet 17 a which has inner and outer side surfaces correspondingto the inner and outer edges, the second annular cut-out sinteredceramic sheet 17 b which has an outer side surface corresponding to theinner edge, and the rest of the outer portion. The first cut-outsintered ceramic sheet 17 a has the fracture surface of the entire innerand outer side surfaces obtained in the shearing process. On the otherhand, the second cut-out sintered ceramic sheet 17 b has the fracturesurface of the entire outer side surface obtained in the shearingprocess and is usable as a high-accuracy part similar to the firstcut-out sintered ceramic sheet. In this manner, designing to furtherprovide another independent shearing site on the inside of the cut-outsintered ceramic sheet allows obtaining not only the margin which is theouter portion of the cut-out sintered ceramic sheet but also the cut-outsintered ceramic sheet wherein the inside is cut out from the desiredshape. That is, as indicated in Example 5, even a cut-out sinteredceramic sheet in a complex shape which has two or more independentsheared surfaces can be produced in a single shearing process. It isalso possible to divide the process into separate processes to form twosheared surfaces with a differently-timed operation.

Accordingly, by using the present invention, the sintered ceramic sheet6 can be formed into the cut-out sintered ceramic sheet having variousshapes simply by changing shapes of the upper-side die 2 a and thelower-side die 2 b. In Examples 1-5, the clearance X is set assubstantially 10 μm. A squared ferrite slab of substantially 100 mm on aside and 170 μm in thickness is employed for the sintered ceramic sheet6 of the present embodiment. Further, a polyimide sheet of substantially30 μm in thickness is employed for the plastic resin film. However,processing conditions of the shearing device, and/or, the shape, sizeand material may be optionally designed by those skilled in the artdepending on the usage of the cut-out sintered ceramic sheet.

A side surface of the cut-out sintered ceramic sheet obtained by theabove methods is a fracture surface including reliefs at its entiresurface as shown in FIG. 21. The fracture surface is a surface that iscut out after the sintering and that does not include any marks ofprocessing. Since the side surface is not processed, the side surfacecomes to be a surface having the reliefs instead of being flat. Theimage in FIG. 21 is taken through a scanning electron microscope (SEM)with 100× magnification.

Since the fracture surface is not processed, the sintered state of thefracture surface does not change, thus the properties thereof do notchange. That is, the sintered state of the cut-out sintered ceramicsheet obtained in the shearing process is uniform both in the fracturesurface having the reliefs and the other portion. For example, when alaser process is performed, the properties may deteriorate due to thesintered state of the side surface changed by heat.

The cut-out sintered ceramic sheet may have the plastic resin film 9adhered at least on one surface of the upper and lower surfaces. Thatplastic resin film 9 is adhered to one of the surfaces of the upper andlower surfaces up to an end portion.

The above characteristics are achieved by the manufacturing method ofthe present invention. For example, when the film-adhered ceramic sheet10 is laser processed, the cut-out sintered ceramic sheet after theprocessing may have the end portion of the plastic resin film 9 meltedor deformed by the heat, whereby the end portion of the cut-out sinteredceramic sheet may not be covered completely by the plastic resin film 9.Further, when the film-adhered ceramic sheet 10 is subjected to a dicingprocess, when a rotary knife rotating at high speed cuts ceramic, theplastic resin film 9 may be deformed at the same time, so the endportion of the cut-out sintered ceramic sheet may not be coveredcompletely by the plastic resin film 9, similar to the case of the laserprocess. Accordingly, when pressure is exerted from outside to a portionthat is not covered by the plastic resin film 9, the cut-out sinteredceramic sheet breaks easily. Or, even if the plastic resin film isadhered onto the sintered ceramic sheet 6 after the sintered ceramicsheet 6 is cut in the dicing process, there is difficulty in adheringthe plastic resin film 9 onto the sheet securely to avoid being out ofalignment with the edge. This is likely to cause an exposed portion notcovered by the plastic resin film 9. Similar to this case, when pressureis exerted from outside to a portion that is not covered by the plasticresin film 9, the cut-out sintered ceramic sheet breaks easily.

By using the present invention, the plastic resin film can be adheredfully up to the end portion of the cut-out sintered ceramic sheet, andthe cut-out sintered ceramic sheet can be protected from outsidepressure.

As described above, the present invention has very good dimensionalaccuracy since it processes the sintered ceramic sheet after thesintering. Further, simply by shearing the sintered ceramic sheet usingthe die, the sintered ceramic sheet can be formed into the desiredshape, thus the cut-out sintered ceramic sheet can be produced quicklyand efficiently. More specifically, in the method of manufacturing acut-out sintered ceramic sheet in the embodiments, the sintered ceramicsheet is sheared by sandwiching and fixing one side of the sinteredceramic sheet with the contact surface of the upper die and the contactsurface of the second pressing module, and at the same time, sandwichingand fixing the other side of the sintered ceramic sheet with the contactsurface of the lower die and the contact surface of the first pressingmodule, and then relatively displacing the upper and lower die with thepredetermined load. This prevents a localized and momentary strongstress (warpage) and an impact generated in shearing at the shearingposition or in proximity thereof, and therefore prevents brittlefracture on the fracture surface of the cut-out sintered ceramic sheet.That is, the method of manufacturing the cut-out sintered ceramic sheetin the present invention has an advantage of reducing burrs or cracks onthe fracture surface of the cut-out sintered ceramic sheet.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology, which has been used, is intended to bein the nature of words of description rather than limitation. Manymodifications and variations of the invention are possible in light ofthe above teachings. Therefore, within the scope of the appended claims,the invention may be practiced other than as specifically described.

What is claimed is:
 1. A method of manufacturing a cut-out sinteredceramic sheet, the method comprising: a first step of obtaining a formedceramic green sheet by forming the ceramic green sheet; a second step ofobtaining a sintered ceramic sheet by sintering the formed ceramic greensheet; a third step of obtaining a film-adhered ceramic sheet byadhering a plastic resin film onto which adhesive is applied on at leastone surface of the sintered ceramic sheet; and a fourth step of shearingthe film-adhered ceramic sheet along edges of an upper die and a lowerdie to form a sheared film adhered ceramic sheet; wherein: thefilm-adhered ceramic sheet is sheared by sandwiching and fixing thefilm-adhered ceramic sheet between the upper die and a second pressingmodule juxtaposed on the lower die, while simultaneously sandwiching andfixing the film-adhered ceramic sheet between the lower die and a firstpressing module juxtaposed on the upper die; the upper and lower diesare then linearly displaced with a predetermined load to shear thefilm-adhered ceramic sheet; and a clearance is provided and maintainedbetween the edges of the upper and lower dies such that the upper andlower dies do not directly contact a resulting surface of a fracturesite.
 2. The method of manufacturing a cut-out sintered ceramic sheetaccording to claim 1, wherein the fourth step includes separating thefilm-adhered ceramic sheet into a desired-shaped cut-out sinteredceramic sheet and an outer portion by shearing off the film-adheredceramic sheet into the desired-shaped cut-out.
 3. The method ofmanufacturing a cut-out sintered ceramic sheet according to claim 1,wherein a clearance (X) between each edge is about 5-50 μm.
 4. Themethod of manufacturing a cut-out sintered ceramic sheet according toclaim 1, wherein the plastic resin film is selected from the groupconsisting of polyester, polyimide, polyimide varnish and epoxy resin.5. The method of manufacturing a cut-out sintered ceramic sheetaccording to claim 1, wherein the edges of the upper and lower dies havesubstantially the same shape as the outer shape of a desired cut-outsintered ceramic sheet, and the film-adhered ceramic sheet is separatedinto the desired-shaped cut-out sintered ceramic sheet and an outerportion.
 6. The method of manufacturing a cut-out sintered ceramic sheetaccording to claim 5, wherein either one of the upper and lower dies hasan annular contacting surface with inner and outer edges, and thefilm-adhered ceramic sheet is separated into a first annular cut-outsintered ceramic sheet, a second cut-out sintered ceramic sheet cutalong the inner edge and an outer portion.
 7. The method of claim 1,wherein the ceramic sintered sheet comprises at least one of alumina,zirconia, titanium, silica, aluminum nitride, silicon nitride, siliconcarbide, cordierite, or mullite.
 8. The method of claim 1, wherein thesheared film adhered ceramic sheet is substantially free of burrs alongthe resulting surface of the fracture site of the sheared sinteredceramic sheet.
 9. The method of claim 1, wherein the sheared filmadhered ceramic sheet is substantially free of burrs along the resultingsurface of the fracture site of the sheared sintered ceramic sheet.